1,721,110 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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Light Transfer Simulation Tools in Photobiological Fuel Production
Get PDFPhotobiological carbon dioxide fixation and fuel production have received significant attention in recent years as sustainable solutions to global warming and energy crisis. However, this technology suffers from low production rates, poor solar energy conversion efficiency, and relatively high cost compared with competing technologies. The objective of the present study is to address these limitations by developing efficient and reliable simulation tools to optimize photobiological fuel production systems.First, an efficient radiative transfer equation (RTE) solver was developed using the discontinuous Galerkin (DG) method and graphics processing units (GPUs). In this study, the RTE solver was validated with benchmark problems related to combustion systems. In addition, this study demonstrated computational benefits of GPUs computing for solving the RTE.Second, the spectral effective real and imaginary parts of the complex index of refraction of green microalgae Chlamydomonas reinhardtii were retrieved from the its experimentally measured radiation characteristics. The microalgae were considered as spherical cells with equivalent diameter distributions. Genetic algorithm and Lorentz-Mie theory were used as inverse and forward method, respectively. In addition, T-matrix was used to predict the radiation characteristics of filamentous cyanobacteria consisting of aligned and connected spheres. This study established that, from a light absorption and scattering point of views, these microorganisms can be treated as infinitely long cylinders with volume-equivalent diameter. The methodology can be used in a wide range of applications and the results can be used to predict the radiation characteristics of PBR suspensions.Finally, light transfer in photobioreactors (PBRs) containing microalgae C. reinhardtii was modeled using the previously developed RTE solver. Then, the light transfer and growth kinetics were combined to estimate the daily biomass productivity of outdoor open ponds, vertical flat-plate PBRs, and tubular PBRs. The effects of growth kinetics models and cellular respiration on daily biomass productivity were investigated. The study demonstrated that the daily productivity per unit of illuminated surface area for PBRs operated in batch mode were identical and depended uniquely on the ratio X0/a where X0 is the initial microalgae concentration and a is the illuminated surface area per unit volume of PBR. Similar results were obtained with experimental data and other simulation results reported in the literature, for different microorganisms and PBRs operated in continuous mode. The PBR optical thickness, represented by X0/a, constitutes a convenient parameter for designing (via a) and operating (via X0) these PBRs to achieve their maximum performance
Controlling Thermal Conductivity in Mesoporous Silica Films Using Pore Size and Nanoscale Architecture
No full textThis work investigates the effect of wall thickness on the thermal conductivity of mesoporous silica materials made from different precursors. Sol-gel- and nanoparticle-based mesoporous silica films were synthesized by evaporation-induced self-assembly using either tetraethyl orthosilicate or premade silica nanoparticles. Since wall thickness and pore size are correlated, a variety of polymer templates were used to achieve pore sizes ranging from 3-23 nm for sol-gel-based materials and 10-70 nm for nanoparticle-based materials. We found that the type of nanoscale precursor determines how changing the wall thickness affects the resulting thermal conductivity. The data indicate that the thermal conductivity of sol-gel-derived porous silica decreased with decreasing wall thickness, while for nanoparticle-based mesoporous silica, the wall thickness had little effect on the thermal conductivity. This work expands our understanding of heat transfer at the nanoscale and opens opportunities for tailoring the thermal conductivity of nanostructured materials by means other than porosity and composition.
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Modeling and simulations of electrical energy storage in electrochemical capacitors
Get PDFThe present study investigates transport and electrochemical phenomena in electrochemical capacitors (ECs) for electrical energy storage applications. Modeling of such systems is made difficult by the complex multidimensional and multiscale porous electrode structures along with the coupled physical phenomena and redox reactions. This study is unique in that it presents rigorous development of physical models for electric double layers and redox reactions in ECs. These models were used to gain insights into the coupled transport and electrochemical phenomena involved. Finally, the results were used to identify the dominant design parameters.First, this study identified the important physical phenomena that must be accounted for when simulating electric double layer capacitors (EDLCs). It established that the Stern and diffuse layers, the finite ion sizes, and the field-dependent electrolyte permittivity must all be accounted for. To account for the Stern layer for 3D electrode structures along with all the other phenomena, a new set of boundary conditions was derived. In fact, this study presents the first simulations of EDLCs with 3D electrode structures including (i) ordered mesoporous carbon sphere arrays and (ii) ordered bimodal mesoporous carbons, respectively. The model and numerical tools were validated successfully against experimental data.Second, this study derives a scaling law for the integral areal capacitance of carbon-based EDLCs supported by rigorous analysis and experimental data for various mesoporous carbon electrodes with different electrolytes. It establishes that the integral areal capacitance of porous electrodes can be expressed as the product of the capacitance of planar electrodes and a semi-empirical function to correct for the porous electrode morphology. To maximize the integral areal capacitance, the electrolyte should have small ion effective diameter and large dielectric constant. The electrode pore diameter should be tailored as monodispersed as possible to match the ion diameter.Third, this study presents dynamic modeling of EDLCs accounting for charge transport in both the electrode and electrolyte. It provides rigorous physical interpretations of experimental observations from electrochemical impedance spectroscopy and cyclic voltammetry (CV) experiments based on physics-based numerical simulations. Moreover, a generalized modified Poisson-Nernst-Planck (GMPNP) model was derived from first principles to simulate electric double layer dynamics valid for asymmetric electrolytes and/or in the presence of multiple ion species. For the first time, a self-similar behavior was identified for the electric double layer integral capacitance estimated from CV measurement simulations.Finally, this study presents dynamic modeling of asymmetric supercapacitors in CV measurements by rigorously and simultaneously accounting for electric double layers and redox reactions as well as ion insertion in the electrode. It establishes that in CV measurements of pseudocapacitive materials: (i) the capacitive current varies linearly with scan rate and (ii) the Faradaic current is proportional to .The models and results could help develop the optimum electrode architecture to achieve maximum energy and power densities. Moreover, these models will also be useful for simulating and designing various practical electrochemical, colloidal, and biological systems for a wide range of applications
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